Personally, I do not know if you can do anything to that brush to bring it back to life. Never had one go like that at least not yet.
I do think you are being a little heavy handed when making your lather. There is no need to mash any brush near flat to make lather. Regardless of the quality of the brush it is not good for any brush. A poor quality brush will die faster from being treated that way, almost immediately in the case of yours.
There are some very good vids on how to make a lather and it might be a good idea, as previously suggested, to watch a few of them. Even hard triple milled soaps do not need a heavy hand on the brush to load up the brush with soap and then make a lather with.
Bob